U.S. patent application number 12/820529 was filed with the patent office on 2010-12-30 for wind power plant predictive protection circuit.
This patent application is currently assigned to VESTAS WIND SYSTEMS A/S. Invention is credited to Peter Nielsen, Kim Sveinsson Sorensen.
Application Number | 20100327599 12/820529 |
Document ID | / |
Family ID | 43020421 |
Filed Date | 2010-12-30 |
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United States Patent
Application |
20100327599 |
Kind Code |
A1 |
Nielsen; Peter ; et
al. |
December 30, 2010 |
WIND POWER PLANT PREDICTIVE PROTECTION CIRCUIT
Abstract
The present invention relates to a method of operating of a wind
power plant comprising a circuit breaker and at least one wind
turbine generator electrically connectable to an electrical grid
through said circuit breaker, the method comprising the steps of
detecting at least one condition for the circuit breaker to trip by
means of a sensor; informing a control means of this detection
prior to the circuit breaker disconnecting; and preparing the at
least one wind turbine generator before said circuit breaker
disconnects said at least one wind turbine generator from said
electrical grid.
Inventors: |
Nielsen; Peter; (Fredericia,
DK) ; Sorensen; Kim Sveinsson; (Ry, DK) |
Correspondence
Address: |
WOOD, HERRON & EVANS, LLP
2700 CAREW TOWER, 441 VINE STREET
CINCINNATI
OH
45202
US
|
Assignee: |
VESTAS WIND SYSTEMS A/S
Randers SV
DK
|
Family ID: |
43020421 |
Appl. No.: |
12/820529 |
Filed: |
June 22, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61223723 |
Jul 8, 2009 |
|
|
|
Current U.S.
Class: |
290/55 |
Current CPC
Class: |
H02J 3/386 20130101;
Y02E 10/72 20130101; Y02E 10/763 20130101; Y02E 10/76 20130101;
F03D 7/0284 20130101; F05B 2270/107 20130101; F03D 9/255 20170201;
H02J 3/381 20130101; H02J 2300/28 20200101; H02P 9/10 20130101;
F03D 7/0288 20130101; Y02E 10/723 20130101 |
Class at
Publication: |
290/55 |
International
Class: |
F03D 9/00 20060101
F03D009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2009 |
DK |
PA 2009 00812 |
Claims
1. A method of operating a wind power plant, said wind power plant
comprising a circuit breaker and at least one wind turbine
generator electrically connectable to an electrical grid through
said circuit breaker, the method comprising the steps of: detecting
at least one condition for the circuit breaker to trip by means of
a sensor; informing a control means of this detection prior to the
circuit breaker disconnecting; and preparing the at least one wind
turbine generator before said circuit breaker disconnects said at
least one wind turbine generator from said electrical grid.
2. The method according to claim 1, wherein said sensor comprises a
current transducer adapted to sense an electrical current through
said circuit breaker, and wherein said condition is related to the
current detected by the current transducer.
3. The method according to claim 1 or 2, wherein the control means
is informed and action is taken within 100 ms, such as within 75
ms, such as within 50 ms, from the determination that the circuit
breaker will trip.
4. The method according to any of the preceding claims, wherein the
step of preparing the at least one wind turbine generator comprises
initiating a fast ramp down of the P and Q set points for the at
least one wind turbine generator.
5. The method according to any of the preceding claims, wherein the
step of preparing the at least one wind turbine generator comprises
sending a pre-warning to any equipment within the wind power
plant.
6. The method according to any of the preceding claims, wherein the
circuit breaker is adapted to trip when the sensor detects that the
current (I) exceeds the current grading curve for the circuit
breaker.
7. The method according to any of the preceding claims, wherein the
wind power plant further comprises additional electrical equipment
installed between the at least one wind turbine generator and the
circuit breaker.
8. The method according to any of the preceding claims, wherein the
detection of at least one condition for the circuit breaker to trip
is made by the sensor by an indirect measurement.
9. A wind power plant comprising a circuit breaker and at least one
wind turbine generator electrically connectable to an electrical
grid through said circuit breaker, said wind power plant further
comprising sensor means for detecting at least one condition for
the circuit breaker to trip, wherein the said sensor means is
arranged for informing a control means of this detection prior to
the circuit breaker disconnecting the at least one wind turbine
generator from said electrical grid, and wherein said control means
is arranged to prepare the at least one wind turbine generator
before said circuit breaker disconnects the at least one wind
turbine generator from said electrical grid.
10. A wind power plant according to claim 9, wherein said sensor
means comprises a current transducer adapted to sense an electrical
current through said circuit breaker, and wherein said condition is
related to said current detected by said current transducer.
11. A wind power plant according to claim 9 or 10, wherein the
control means is adapted to be informed and adapted to take action
within 100 ms, such as within 75 ms, such as within 50 ms, from the
determination that the circuit breaker will trip.
12. A wind power plant according to any of claims 9-11, wherein
said control means is arranged to prepare the at least one wind
turbine generator by initiating a fast ramp down of the P and Q set
points for each wind turbine generator.
13. A wind power plant according to any of claims 9-12, wherein
said control means is arranged to prepare the at least one wind
turbine generator by including pre-warning to any equipment within
the wind power plant.
14. The wind power plant according to any of claims 9-13, wherein
the circuit breaker is adapted to trip when the sensor detects that
the current (I) exceeds the current grading curve for said circuit
breaker.
15. The wind power plant according to any of claims 9-14, wherein
the wind power plant further comprises additional electrical
equipment installed between the at least one wind turbine generator
and the circuit breaker.
16. The wind power plant according to any of claims 9-15, wherein
the detection of at least one condition for the circuit breaker to
trip is made by the sensor by an indirect measurement.
17. The wind power plant according to any of claims 9-16, wherein
the wind power plant further comprises at least one feeder, said at
least one feeder comprising a circuit breaker, a sensor, at least
one wind turbine generator, and a feeder controller being arranged
to take action to prepare each of the wind turbine generators
within the feeder prior to the circuit breaker actually
disconnecting at least one wind turbine generator from said
electrical grid.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S.
Provisional Application No. 61/223,723, filed Jul. 8, 2009, and
claims priority under 35 U.S.C. .sctn. 119 to Danish Patent
Application 2009-00812, filed Jun. 30, 2009. The content of each of
these applications is hereby incorporated by reference herein in
its entirety for all purposes.
FIELD OF THE INVENTION
[0002] The present invention relates to a wind power plant, and the
operation thereof, said wind power plant comprising a circuit
breaker and at least one wind turbine generator. It is particularly
related to, but in no way limited to, a wind power plant
circuit.
BACKGROUND OF THE INVENTION
[0003] In the electrical power generation industry, power producing
turbines are used to generate electrical power for transmission to
a user supply network, known as a grid. Each form of turbine has
its own issues during manufacturing and operation. For example,
wind turbines are normally erected in clusters, known as wind power
plant or wind farms, in locations, which have undergone a rigorous
selection process. This selection process normally places wind
turbine farms at a significant distance from the end users of the
electricity that they will generate.
[0004] The individual turbines are normally grouped into a number
of turbines, collectively known as a feeder, the outputs from which
are brought together and fed to the grid via a sub-station. The
substation includes a sub-station transformer arranged to adjust
the output of the farm (voltage) to match the requirements of the
grid. In order to protect the sub-station and the grid beyond from
problems arising from individual turbines or feeders, such as
transient short circuit current due to short circuits, each feeder
is coupled to the sub-station through an individual circuit
breaker, i.e., feeder circuit breaker. The circuit breaker is
tripped in response to a transient in the feeder current (I) the
output of which is constantly monitored by a current sensor. The
acceptable behaviour of the feeder is illustrated as an example in
the grading curve (I, t) of FIG. 3, which indicates that the
circuit breaker is only triggered if the current exceeds a
pre-determined value for more than a predetermined acceptable
period of time. In other words, if the current/time characteristic
of the feeder is above the curve in FIG. 3, then the circuit
breaker will be tripped.
[0005] Although the prompt action of the circuit breaker protects
the substation and the grid, it can cause serious damage, in some
circumstances, to one or more of the wind turbine generators (WTG)
due to the removal of the load from the feeder circuit. This damage
can be both electrical and mechanical. Each wind turbine generator
is behind their circuit breaker and damage protected by its own
protection system, but unexpected opening of the circuit breaker
may put some high loads to the mechanical structure of each wind
turbine generator. The present invention can reduce the high loads
by pre-warning the wind turbine about an upcoming event. The damage
can also happen to the substation transformer or other electrical
equipment, connected to the electrical circuit within the wind
power plant, due to extreme high current transient.
[0006] The present invention addresses the issue of damage done to
the wind turbine generator or the wind power plant due to the
tripping of a circuit breaker and as stated above is pertinent to
any type of generator used in electrical power generation. However,
the invention will be described with reference to wind turbine
generators, and to the damage that can be avoided to key components
of the wind turbine generator or cluster of turbine and other
electrical equipment within the wind power plant.
[0007] The components in wind turbine generator include those
components specifically involved in the generation of electrical
power, such as blade, hub, gearbox (optional), tower, generator and
power converter (optional) and those components which are of a
secondary nature, which are known as auxiliary components. All of
the aforementioned components are described below with reference to
FIGS. 1 and 2.
[0008] If the main circuit goes off line because of the tripping of
a circuit breaker or feeder circuit breaker, serious damage can be
done to the turbine and the auxiliary circuit components. For
example, mechanical loads, drive trains oscillations, uncontrolled
behavior, if the invention is not applied, there is a need for at
faster response to control the drive train, such as faster pitch
speed.
[0009] Nonetheless, circuit breakers have been employed in power
generation plants for many years because the possible damage to the
turbines has been considered to be less important than the damage
to the grid, that would otherwise be caused by a short circuit.
BRIEF SUMMARY OF THE INVENTION
[0010] This section is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description of the Invention. Thus, this section is
not intended to identify key features or essential features of the
claimed subject matter, nor is it intended to be used as an aid in
determining the scope of the claimed subject matter.
[0011] According to a first aspect of the present invention, there
is provided a method of operating a wind power plant, said wind
power plant comprising a circuit breaker and at least one wind
turbine generator electrically connectable to an electrical grid
through said circuit breaker, the method comprising the steps
of:
[0012] detecting at least one condition for the circuit breaker to
trip by means of a sensor;
[0013] informing a control means of this detection prior to the
circuit breaker disconnecting; and
[0014] preparing the at least one wind turbine generator before
said circuit breaker disconnects said at least one wind turbine
generator from said electrical grid.
[0015] Preferably, the detection means is based on a current sensor
and wherein said current sensor is sensing an electrical current
through said circuit breaker, and wherein said condition is related
to the current detected by the sensor.
[0016] Preferably, the generator control means is informed and
action is taken within 100 ms from the determination that the
circuit breaker must be tripped, most preferably in between 50 and
100 ms.
[0017] Preferably, the action which is taken to protect the
generator is a fast ramp down of the P and Q set points of the
turbine.
[0018] Alternatively, the action taken to protect the individual
wind turbine generator includes one or more of the following
reduction in the reactive power and/or active power, the latter is
often done by pitching the aerodynamic rotor blades of the
turbine.
[0019] In this embodiment, the circuit breaker is tripped when
current (I), as detected by the sensor, exceeds the current grading
curve for the circuit.
[0020] Preferably, the wind power plant further comprises
additional electrical equipment installed between at least one wind
turbine generator and the circuit breaker.
[0021] In an embodiment, the detection of at least one condition
for the circuit breaker to trip is made by the sensor by an
indirect measurement.
[0022] In a preferred embodiment, the external circuit is a user
supply circuit or an electrical power grid.
[0023] According to a second aspect of the present invention, there
is provided a wind power plant comprising a circuit breaker and at
least one wind turbine generator electrically connectable to an
electrical grid through said circuit breaker, said wind power plant
comprising:
[0024] means for detecting at least one condition for the circuit
breaker to trip; and
[0025] control means being arranged to prepare the at least one
wind turbine generator before said circuit breaker disconnects the
at least one wind turbine generator from said electrical grid.
[0026] Preferably, the sensor means is arranged to inform the
control means of the condition detection prior to the circuit
breaker disconnecting the at least one wind turbine generator from
the electrical grid.
[0027] In an embodiment, the wind power plant comprises a plurality
of wind turbine generators grouped into one or more individual
feeders, each feeder having a feeder controller, a circuit breaker
and a sensor and a least one wind turbine generator, the feeder
controller taking action to protect each of the generators within
the feeder prior to the circuit breaker actually disconnecting the
feeder from the output to the external circuit.
[0028] Many of the attendant features will be more readily
appreciated as the same become better understood by reference to
the following detailed description considered in connection with
the accompanying drawings. The preferred features may be combined
as appropriate, as would be apparent to a skilled person, and may
be combined with any of the aspects of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The present invention will now be explained in further
details with reference to the accompanying figures, wherein
[0030] FIG. 1 is a schematic diagram of the exterior of a known
wind turbine;
[0031] FIGS. 2A, 2B and 2C are block diagrams of various wind
turbine configurations;
[0032] FIG. 3 is a graph of the grading curve of a power generator
circuit in accordance with an aspect of the present invention;
[0033] FIG. 4 is a circuit diagram of a power generator circuit in
accordance with the present invention;
[0034] FIG. 5 is a circuit diagram of a plurality of generators, as
described in FIG. 4, grouped into a feeder arrangement in
accordance with the present invention; and
[0035] FIG. 6 is a flow diagram of a method of operation of the
feeder of FIG. 5 or individual generators therein, as detailed in
FIG. 4, in accordance with an aspect of the present invention.
[0036] Common reference numerals are used throughout the figures to
indicate similar features.
[0037] While the invention is susceptible to various modifications
and alternative forms, specific embodiments have been shown by way
of example in the figures and will be described in detail herein.
It should be understood, however, that the invention is not
intended to be limited to the particular forms disclosed. Rather,
the invention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Embodiments of the present invention are described below by
way of example only. These examples represent the best ways of
putting the invention into practice that are currently known to the
Applicant although they are not the only ways in which this could
be achieved.
[0039] The invention will be described herein with reference to
wind turbine generators, although it can be implemented utilising
any power generator system.
[0040] Regarding the figures, FIG. 1 illustrates a schematic
representation of the exterior of a known wind turbine generator 2.
FIG. 1 illustrates the turbine rotor 4, which is coupled to the
main shaft 6 of the turbine 2. The nacelle 8 is in turn supported
by the turbine tower 10. The nacelle 8 and the tower 10 houses the
bulk of the components of the turbine, including a wind turbine or
generator controller 16, which is a computer processor arranged to
control the operation of the wind turbine 2. The controller 16
controls all equipment in the wind turbine 2 based on input from
sensors or estimators. The controller 16 also controls the angle of
the blades of the wind rotor. The turbine 2 is shown with a
transformer 12, which is positioned at ground level and may be
remote from the tower 10. Often the transformer is located in the
nacelle or in the tower. The transformer 12 can also be seen as a
substation transformer. In addition, as illustrated in FIG. 5, the
sub-station transformer 12 may be coupled to a plurality of
turbines 2, which may be grouped into feeders 44 as will be
discussed in more detail below.
[0041] Outside the wind turbine generator, the current is
transmitted to the sub-station transformer 12, along cables 14,
from which the grid 34 is fed. An optional wind turbine transformer
40 will transform the output voltage of the generator 30, being in
the range of 400-6000 V, to a higher level at approximately 6 to 36
kV. The sub-station transformer 12 will transform the voltage to an
even higher level at approximately 100 to 400 kV
[0042] FIGS. 2A-C illustrate different topologies of single wind
turbine generators in accordance with the present invention. FIG.
2A-2C all have an electrical generator 30. The electrical generator
can be an AC induction generator, synchronous generator with
excitation winding, or a permanent magnet synchronous generator.
The listed generator types are examples and the invention should
not be limited to these types of generators.
[0043] FIG. 2A illustrates a wind turbine generator with a rotor 4,
main shaft 6 connected to a gear 28, with a low speed side and a
high speed side, the high speed side is connected to an electrical
generator 30. The electrical output of the generator is transformed
to a higher voltage level in a turbine transformer 40 and the
output is fed to an electrical grid 34 through a circuit breaker
38.
[0044] FIG. 2B illustrates another wind turbine with a rotor 4,
main shaft 6 connected to a gear 28, with a low speed side and a
high speed side, the high speed side is connected to an electrical
generator 30. The electrical output of the generator 30 is fed to a
frequency converter 31 allowing the output frequency of the
generator 30 to vary in relation to the nearly fixed frequency at
the grid 34. The output the frequency converter 31 is transformed
to a higher voltage level in a turbine transformer 40 and the
output is fed to an electrical grid 34 through a circuit breaker
38.
[0045] FIG. 2C illustrates another wind turbine with a rotor 4
connected to a low speed electrical generator 30. The electrical
output of the generator is fed to a frequency converter 31 allowing
the output frequency of the generator 30 to vary in relation to the
nearly fixed frequency at the electrical grid 34. The output the
frequency converter 31 is transformed to a higher voltage level in
a turbine transformer 40 and the output is fed to an electrical
grid 34 through a circuit breaker 38.
[0046] The wind turbine generator 2 is connected to an electrical
grid 34 through a circuit breaker 38 allowing the wind turbine
generator to be disconnected from the grid. Disconnection from the
grid can be needed for service purpose, but it can also be the
result of an over current in the circuit breaker 38. The over
current can happen due to short circuits either in the wind turbine
or somewhere in the electrical grid 34. The result of a short
circuit on either side of the circuit breaker can cause damage on
the electrical as well as on the mechanical component of the wind
turbine 2.
[0047] Embodiments of the present invention are intended for
protecting the electrical and mechanical equipment from the damage
that may happen when the circuit breaker 38 disconnects a wind
turbine generator or even a wind power plant. The disconnection of
a circuit breaker 38 will create sudden changes to the system
within the wind power plant, that again will generate electrical
transients and cause high mechanical loads a the wind turbine 2.
Situations that may result in component failure on any components
in the wind power plant, especially power converters 31 and
transformers 12, 40 are sensitive to high transients.
[0048] A circuit breaker 38 is an automatically operated electrical
switch designed to protect an electrical circuit from damage caused
by overload or short circuit. Its basic function is to detect a
fault condition and, by tripping, interrupting continuity, to
discontinue electrical flow. Unlike a fuse, which operates once and
then has to be replaced, a circuit breaker 38 can be reset (either
manually or automatically) to resume normal operation. Circuit
breakers 38 are made in varying sizes, from small devices that
protect an individual household appliance up to large switchgear
designed to protect high voltage circuits feeding an entire
city.
[0049] Some circuit breakers 38 use a solenoid (electromagnet)
which pulling force increases with the current. The circuit breaker
contacts are held closed by a latch. As the current in the solenoid
increases beyond the rating of the circuit breaker, the solenoids
pull releases the latch which then allows the contacts to open by
spring action. The core is restrained by a spring until the current
exceeds the breaker rating.
[0050] Thermal magnetic circuit breakers 38 incorporate both
techniques with the electromagnet responding instantaneously to
large surges in current (short circuits) and the bimetallic strip
responding to less extreme but longer-term over-current
conditions.
[0051] Medium-voltage circuit breakers are often operated by
current sensing protective relays operated through current
transducers such as current transformers 42. Medium-voltage circuit
breakers nearly always use separate current transducers and
protection relays, instead of relying on built-in thermal or
magnetic over current transducers.
[0052] FIG. 3 illustrates the grading curve for the normal
operation of a power generator circuit including a generator 30 and
a circuit breaker 38. The protection relays ensures that the
circuit breaker 38 is tripped when the current (I) in the circuit
exceeds the permitted current for more than a predetermined time
(grading curve), as will be discussed below.
[0053] FIG. 4 illustrates an embodiment of a power generator
circuit in accordance with the present invention including a single
generator 30 in the form of a wind turbine generator 2. As well as
the generator 30 the circuit includes a transformer 40 and a
controller 16 which are locate within a nacelle 8 in this
embodiment. In addition, the circuit includes a circuit breaker 38
and a current sensor 42. Current in the circuit is monitored by the
sensor 42 and the circuit breaker 38 is tripped if the current
exceeds a predetermined grading characteristic, as discussed above.
For protection, the grading curve is coordinated with the
controller 16, so when the current through circuit breaker 38
exceeds the grading curve (I,t) and the circuit breaker 38 is bound
to trip. Typically, a delay of 50-100 ms is introduced before the
wind turbine is actually disconnected. This delay can be used to
prepare the turbine for the disconnection, by initiating a fast
ramp down of P and Q set-points to the turbines 2 in the feeder
affected. This control action will decrease the stress mechanically
and electrically at the instant of the trip or even assure a
completely controlled stop of all affected turbines.
[0054] FIG. 5 illustrates an embodiment of the present invention
wherein a plurality of individual generators 30 (or turbines 2) is
grouped into individual feeders 44, each equipped with a circuit
breaker 38 for protection of the generators 30 (or turbines 2) in
that feeder.
[0055] Each of the individual generators 30 is coupled through a
transformer 40 to an output 46 for that feeder 44. Each output 46
is coupled to a sub-station 48. The sub-station 48 includes a
sub-station circuit breaker 38 and a transformer 12 which produces
an output which is suitable for the external circuit, normally an
electrical circuit or grid 34. The circuit also includes feeder
circuit breakers 38 and feeder controllers 50 each of which is
arranged to control the operation of each of the generators 30
within one of the feeders 44. In another embodiment, the feeder can
also have a feeder transformer 12 (not shown).
[0056] The sub-station may also have various electrical equipment
61 for providing control of voltage level and reactive power, such
equipment can be switched capacitors, statcom, etc.; all equipment
that would be known to person skilled in the art of wind power
plants. Often the substation also have a plant or park controller
60 that can communicate with all equipment in the wind power plant,
this plant controller 60 can be used for preparing the wind
turbines 2 in the event of the tripping of the sub-station circuit
breaker 38.
[0057] If the wind power plant is made with feeders 44, the feeder
controllers 50 may communicate with the plant controller 60, which
again communicates with the wind turbines 2 through the wind
turbine controllers 16. The feeder controllers 50 may also
communicate directly with the wind turbine controllers 16.
[0058] The sensor 42 is coupled to the feeder controller 50 via a
fibre optic cable 52 to enhance the speed of communication there
between. The aforementioned control can include controlling
operation of the mechanisms utilised in the generation of power and
the auxiliary components as detailed above. It can also include
control of individual controllers 16 within each turbine 2.
[0059] In case of an internal fault in a feeder 44 (short circuit),
the current through circuit breaker 38 exceeds the grading curve
(I,t) and the circuit breaker 38 is bound to trip. Typically, a
delay of 50-100 ms is introduced before the feeder is actually
disconnected. By sharing the circuit breaker current measurement 42
value over a fiber connection (TCP/IP or any other communication
protocols) with the plant controller 60, the controller is able to
predict the circuit breaker trip before it actually occurs, due to
the delay. In these 50-100 ms, the plant controller 60 initiates a
fast ramp down of P and Q set-points to the turbines in the feeder
affected. This control action will decrease the stress mechanically
and electrically at the instant of the trip or even assure a
completely controlled stop of all affected turbines.
[0060] FIG. 6 is a flow diagram illustrating a method of operation
of each of the turbines 2, within the feeder 44, as described above
with reference to FIG. 4. In particular, it illustrates a method of
operation in accordance with the present invention in which the
current in the circuit from the generators 30 to the output 46
within each feeder 44 is monitored by a current sensor 42 (Box
100).
[0061] If the current does not exceed the grading curve, as
illustrated in FIG. 3, then no action is taken (Box 102) and the
sensor 42 continues to monitor the current (Box 100). However, if
the current exceeds the grading curve, most likely due to a short
circuit, then the circuit breaker 38 is tripped (Box 104).
[0062] However, when the conditions necessary for the circuit
breaker 38 to trip arise the sensor 42 sends a signal before the
actual disconnection, via a communications channel, to the feeder
controller 50 within the feeder 44 (Box 106). On receipt of this
signal the feeder controller 50 takes action to ameliorate the
effects of the tripping of the circuit breaker 38 (Box 108) prior
to the circuit breaker 38 actually disconnecting the generator 30
from the output 46 to the external circuit 34 (110).
[0063] In particular, the controller 16, 50 or 60 instructs a fast
ramp down of the active power, P, and reactive power, Q, set points
for each generator 30. In addition, the fast ramp down of P would
for a wind turbine generator without a power converter 31 require a
change in the pitch angle of the blades of the rotor 4.
Additionally, a wind turbine generator with a power converter can
ramp down the P set point within the power converter 31, and allow
the wind rotor 4 to accelerate in speed, within an allowed range.
Doing so, the turbine will be ready to support the grid 34 when the
circuit breaker reconnects.
[0064] It is a feature of the present invention that action is
taken by the plant controller 60, feeder controller 50, or the
generator controller 16, to ameliorate the detrimental effects of
the tripping of the circuit breaker 38. In order for this to be
possible, the inventors firstly had to determine that there is a
delay between circumstances that would cause the circuit breaker 38
to trip having arisen and the actual disconnection of the
generators 30 from the output 46 of the feeder 44. Furthermore,
they also had to come to the conclusion that positive action could
be taken to offset the aforementioned effects, which goes against
the long trend in the industry as such delays have for many years
been considered to be an unavoidable result of utilising a circuit
breaker 38, the only redeeming feature of which is that it is
preferable to the damage a short circuit would otherwise do to a
substation 48 or grid 34.
[0065] Whilst the above description relates to wind power plants,
this is by way of example only. The invention is applicable to any
turbine system, such as oil fired or hydro-electric turbines or any
other turbine used in electricity generation.
[0066] In summary, the invention relates to, a method of operating
a wind power plant comprising a circuit breaker and at least one
wind turbine generator electrically connectable to an electrical
grid through said circuit breaker, the method comprising the steps
of detecting at least one condition for the circuit breaker to trip
by means of a sensor; informing a control means of this detection
prior to the circuit breaker disconnecting; and preparing the at
least one wind turbine generator before said circuit breaker
disconnects said at least one wind turbine generator from said
electrical grid.
[0067] Any range or device value given herein may be extended or
altered without losing the effect sought, as will be apparent to
the skilled person.
[0068] It will be understood that the benefits and advantages
described above may relate to one embodiment or may relate to
several embodiments. It will further be understood that reference
to an item refer to one or more of those items.
[0069] It will be understood that the above description of a
preferred embodiment is given by way of example only and that
various modifications may be made by those skilled in the art. The
above specification, examples and data provide a complete
description of the structure and use of exemplary embodiments of
the invention. Although various embodiments of the invention have
been described above with a certain degree of particularity, or
with reference to one or more individual embodiments, those skilled
in the art could make numerous alterations to the disclosed
embodiments without departing from the spirit or scope of this
invention.
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